This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. While the focus of this proposal will be to examine gene-environment interactions related to three polymorhisms associated with vascular disease, it is important to emphasize that the objectives and implications of this project extend beyond this restricted focus. The loong-range objective of this proposal is to establish a unique resource for continued studies of the genetic basis of vascular disease. Specific aims are to" 1. estimate the prevalence in the population of history of recent infection, PCR evidence of Chlamydia pneumoniae in peripheral blood, behavioral factors, family history, and genetic polymorphisms of the endotoxin receptro (CD 14), platelet glycoprotein receptor IIb/IIIa (GpIIb-IIIa), and nitric oxide synthase (NOS). 2. determine the relative risk of these factors for ischemic stroke and for ischemic stroke subtypes. 3. determine the role of recent infection, chronic infection with C. pneumoniae, and behavioral factors (e.g., cigarette smoking, exercise, oral contraceptive use, alcohol intake) in modifying the effect of genotype status on stroke risk.